Welcome to the Winobloggers webpage! Students and professors from different universities meet to discuss their findings on Winogradsky columns they constructed!
We learn how to formulate hypotheses, observe, comment, ask and reply to questions related to our scientific experiments.

Sunday, 20 November 2016

From the 3rd to the 4th week, we observed some
differences. Firstly, we can clearly see that in both columns the water is not
as clear as it used to be, due to the bacteria and the nutrients from the
sediment. Also, a notable difference is the growth of a brown film on the
surface of the bottles. This structure is consisted of microorganisms attaching
to surfaces and developing biofilms. A biofilm is an assemblage of microbial
cells that is irreversibly associated. Biofilm-associated cells can be
differentiated from their suspended counterparts by the generation of an
extracellular polymeric substance (EPS) matrix, reduced growth rates, and the
up- and down- regulation of specific genes.The plastic material of our bottles is
a great environment for microorganisms to growth. (Donlan et al, 2002)It is also important to mention that water system biofilm is highly complex, containing corrosion product, clay
material and filamentous bacteria. As we can see in the
pictures, the concentration of the biofilm in first column is greater from the
second one, even though biofilms can grow in very low and high temperatures. Thus,
we can assume that in the 2nd column, the rapid fluctuation of
temperature affects the bacteria not only directly by limiting the growth of
the no-resistant at high temperatures, bacteria, but also it affects them
indirectly by the overheating of the plastic bottle, that excretes damaging
chemicals. This fact, can reduce even more the growth rates of biofilm. Also,
in both columns the sludge is darker from the previous week, due to the anoxic
conditions. Finally, it is remarkable that after 4 weeks, we can still observe
some Annelida even in the warmth exposed bottle. This fact indicates the
toughness of some organisms on the ecosystem of Lake Vrellis.

In conclusion, the most noticeable
difference from the 3rd week, is the growth of biofilms in both columns
and the effect of rapid fluctuation of the temperature.

Hypothesis: The rapid fluctuation of the temperature on daily basis, reduces the growth rate of the microorganisms in the 2nd Winogradsky column.